Report number CMS-BPH-10-002-001 Version 1
Title: Prompt and non-prompt J-psi cross sections in pp collisions at sqrt(s) = 7 TeV
Deadline for comments 26 Oct 2010; CIT comments in cdsweb: Piotr Traczyk
This is the first measurement of the J-psi cross section at 7 TeV. A preliminary result was presented at ICHEP, in the paper the statistics has been increased with respect to the conference, using the same analysis method. This improved measurement will be presented for approval during the Physics Days, next week. The paper is intended for publication in the European Physical Journal C.[[Report number CMS-BPH-10-002-001 Version 1 Title Prompt and non-prompt J-psi cross sections in pp collisions at sqrt(s) = 7 TeV Submitter roberto.tenchini@cern.ch Date of document 14 Oct 2010 Deadline for comments 26 Oct 2010 Note This is the first measurement of the J-psi cross section at 7 TeV. A preliminary result was presented at ICHEP, in the paper the statistics has been increased with respect to the conference, using the same analysis method. This improved measurement will be presented for approval during the Physics Days, next week. The paper is intended for publication in the European Physical Journal C. http://cdsweb.cern.ch/record/1299853?ln=en
Comments
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Artur:
1) l14: "historical discrepancy": please rephrase, sounds funny.
2) l51: remove rapidity coverage of muon detector: already descried on line 38
3) l56-57: while interesting piece of information, I don't see how relevant it is that there were 1.6 collisions per crossing.
4) l58: "good quality data" is not immediately clear, would suggest to replace with something like "Tracker, the Muon and the luminosity measurement detectors were fully operational".
5) l61: "without any further processing" sounds unclear as to what processing you are referring to. Add a statement about HLT passthrough.
6) line 67: remove "also".
7) l68-74: as a non-expert, it is not clear to me if the MC generators listed here have all the improvements listed on lines 15-19. It would be nice to clarify.
8) l84: define "central" and "forward" in terms of (pseudo)rapidity.
9) l91: would recommend changing "cuts are applied…" to e.g.: "To reduce backgrounds from fake muons …, muon tracks are required to pass the following requirements".
10) l92: I guess it is at least two tracks in the pixel layer, not exactly two?
11) l101: Which mass distributions were used in the fit? I imagine the inclusion of J/Psi into this fit could bias the cross-section measurement? Please clarify how the correction is made, and why/how it does not cause a bias.
12) l144-147: not clear the choice of polarization for non-prompt. Could you please clarify a bit why usage of babar measurement is directly transferable here, and how the comparison of that with EvtGen is a proper evaluation of systematic? What are the settings used in EvtGen?
13) l150, 175 and 181: What values do you assign to these uncertainties?
14) l153: You need to rephrase this sentence: different implies a comparison with something, while there is none here. Would suggest dropping the first sentence, and rephrase the second sentence a little bit.
15) l161: can you motivate the choice of 20%? Maybe a reference?
16) l185: I guess it needs to be "eff_off_track is the muon identification efficiency".
17) l190: "mapped" sounds strange, you have "parameterized" the efficiency.
18) l195: "The efficiency for the "->"The efficiency of the requirement for the…"
19) l199: a bias on which distribution? Eta, Pt? If this is a feature of the method, how come it is not present in MC, allowing you to study it? Can you have derived the corrections from data?
20) l229-232: how are these systematic uncertainties used in the analysis? Do they enter the cross-section measurement? please clarify in text.
21) l330-339: can you give at least a qualitative interpretation of the differences observed in different MC models, e.g. Pythia give a significantly different prediction for the prompt J/Psi's, while for non-prompt it is not so different (at least at high Pt). What could be causing this?
-- Main.smaria - 2010-10-17 
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